From: Martin Str|mberg <ams AT ludd DOT luth DOT se>
Message-Id: <199811231712.SAA03641@father.ludd.luth.se>
Subject: Re: More rand()
To: djgpp-workers AT delorie DOT com (DJGPP-WORKERS)
Date: Mon, 23 Nov 1998 18:12:10 +0100 (MET)
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DJ said:
> If you mean cut-and-paste into stdlib.h, then it needs to follow the
> style of stdlib.h,

Ok. No extern and less white space. Something else?

Could someone write the documentation? I don't think I'm too suited for that
due to my very thorough reading of the Linux man page.

I found that {l,n}rand48 return to big values. If you're going to try those
functions I suggest you use the following implementation instead.


Right,

							MartinS

----- Start new nrand48. ------
unsigned long nrand48(
                      unsigned short state[3]
                      )
{

  next(state);
  return( ((unsigned long)state[2]) * 0x8000
        + ( ((unsigned long)state[1]) >> 1 )
          );

}
----- End new {l,n}rand48. ------

----- Start rand48.h to be included in stdlib.h. -----
/* Copyright (C) 1998 Martin Strömberg. */

/* This function returns a double uniformly distributed in [0, 1). It
   uses an internal state common to all the three functions drand48,
   lrand48 and mrand48. */
double	drand48(void);

/* This function returns a double uniformly distributed in [0, 1). It
   uses the state supplied. */
double	erand48(unsigned short state[3]);

/* This function returns an unsigned integer uniformly distributed in
   [0, 2^31). It uses an internal state common to all the three
   functions drand48, lrand48 and mrand48. */
unsigned long	lrand48(void);

/* This function sets the internal state to the state supplied in
   param[0], param[1] and param[2]. It sets the multiplier to
   (param[5]*2^32 + param[4]*2^16 + param[3]) and the additiver to
   param[6]. */
void	lcong48(unsigned short param[7]);

/* This function returns a signed integer uniformly distributed in
   [-2^31, 2^31). It uses an internal state common to all the three
   functions drand48, lrand48 and mrand48. */
long	mrand48(void);

/* This function returns an unsigned integer uniformly distributed in
   [0, 2^31). It uses the state supplied. */
unsigned long	nrand48(unsigned short state[3]);

/* This function sets the internal state to the supplied
   state. Additionaly this function resets the multiplier and
   additiver (possibly changed by a call to lcong48) to the default. 
   It returns the previous state. */
unsigned short *	seed48(unsigned short state_seed[3]);

/* This function returns a signed integer uniformly distributed in
   [-2^31, 2^31).  It uses the state supplied. */
long	jrand48(unsigned short state[3]);

/* This function sets the high order 32-bits of the internal state
   used by the functions drand48, lrand48 and mrand48. The low order
   16-bits are set to the arbitrary value 0x330e. Additionaly this
   function resets the multiplier and additiver (possibly changed by a
   call to lcong48) to the default. */
void	srand48(long seedval);
----- End rand48.h to be included in stdlib.h. -----